Step 1 - Find your model number
You can find this by looking in your settings or by looking at your device.
Look in settings
Go to settings>General>About. You will see Model Name, there you should see what model iPhone you have. You can also use the Model Number to locate what iPhone size you have.
Step 2 - Identify your iPhone size
Put in your model number in the box provided and click enter. You will then be directed to a new page with all cases in your iPhone size!